Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old November 21st 15, 03:47 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On Sat, 21 Nov 2015, Tim Schwartz wrote:

On 11/20/2015 3:55 PM, Madness wrote:
Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?



Hello,

While I recall that they need the dropping resistor, since you have
a bunch of them, I might try destructive testing, and break one apart to see
if there is an internal resistor or not.

Memory says they always needed a resistor, it's not about too much
voltage, but about needed a limited current. The only time they don't
need a resistor is if there is a resistor built in.

Michael


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Old November 21st 15, 04:01 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On Saturday, November 21, 2015 at 5:38:50 AM UTC-8, Tim Schwartz wrote:
...I might try destructive testing, and break one apart to
see if there is an internal resistor or not.

Regards,
Tim

If you take this approach, it does not have to be destructive. If you own a soldering iron, you can melt the two solder blobs on the bayonet, loosen the cement, and remove the bulb intact. After inspection, you can reglue and resolder, and the lamp will be as good as new.
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Old November 21st 15, 05:41 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

In article ,
Madness wrote:
Thanks for the replies, everyone. I forgot to mention that my lot (about
30) is of vintage GE NE-51's, not the modern "NE-2 w/ plastic lens" variety.



The 1966 GE Glow Lamp Manual says a B1A (NE-51) draws 0.3 mA
with a 220k ohm resistor at 120 volts.


Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)
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Old November 22nd 15, 06:26 PM posted to sci.electronics.repair
MJC MJC is offline
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Default NE-51 Neon Bulbs

In article ,
says...

* As an apprentice project, I built a clock that used four 5x7 blocks of
neons for a digital display.


See
https://picasaweb.google.com/1117418...CEDRICProject?
authuser=0&feat=directlink

Mike.


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Old November 22nd 15, 09:24 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

Madness wrote:
Thanks for the replies, everyone. I forgot to mention that my lot (about
30) is of vintage GE NE-51's, not the modern "NE-2 w/ plastic lens" variety.


Note that many neon bulbs had some sort of radioactive doping to get
them to fire at a lower votage.

I don't have any hard data, but I believe it was thorium up until the late
1940's when the US government decided that radioactive material needed
supervision.

It was found to be simpler to just add a small amount of radioactive
krypton gas to the neon. However the half life of the krypton gas is
about 10 years. So neon bulbs made in 1970 would have about 1/20th of
the krypton still radioactive, which is probably no longer able to
make a difference.

Speaking of radioactivity, if you are looking for an unusual project to
make from them, they can be used to make geiger counters.

I don't think they are very sensitive, but if you live in the US, the
red Fesita Ware department of any thrift shop would make it "go nuts".
:-)

Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379

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Old November 22nd 15, 09:35 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs



"Geoffrey S. Mendelson" wrote in message
...
Madness wrote:
Thanks for the replies, everyone. I forgot to mention that my lot (about
30) is of vintage GE NE-51's, not the modern "NE-2 w/ plastic lens"
variety.


Note that many neon bulbs had some sort of radioactive doping to get
them to fire at a lower votage.

I don't have any hard data, but I believe it was thorium up until the late
1940's when the US government decided that radioactive material needed
supervision.


Most valves have some radioactive material in the cathode coating to
increase emission, gas mantles also have some as it makes the illumination
more intense.

IWHT: the radioactive content of a neon bulb is insignificant compared to
either of those examples.

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Old November 24th 15, 09:32 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On Friday, November 20, 2015 at 3:55:22 PM UTC-5, Madness wrote:
Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?


Mpfffff....

This lamp was used by Zenith and more than a few other manufacturers in the 1950s/1960s as an indicator lamp (on/off) at about the time that radio manufacturers started to become concerned about user-servicing and hot-chassis radios - something that never really bothered them in the past. The worked on the theory that a neon lamp was far less likely to burn out than the old standby #44 or #47, so that loose fingers were less likely to get nipped. ASIDE: Audio devices held on to incandescent lamps (With specific reference to the 47) well into the 80s, before shifting - very slowly - to LEDs or Fluorescent lamps. But, they had transformers on board to isolate the chassis.

It is designed to operate at ~120V AC. It _CAN_ operate at ~120V DC, but only one post will light. It will trip (glow) at about 90V +/-.

Unless there is a voltage dropper in the circuit, it will fail quickly at 220 or 240 V - that is voltages outside of Japan and the Americas. As supplied, it has a 100K resistor in series with the lamp. For conversion to 220V, I have heard values of up to an *additional* 220K in series. Try there and work back if you wish to operate at 220V.

As about 2/3 of my hobby time is dedicated to vintage radios, I am quite familiar with, and keep a bunch of these lamps in my spares-box.

Peter Wieck
Melrose Park, PA
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Old November 27th 15, 05:58 PM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs

On 11/24/2015 3:32 PM, wrote:
On Friday, November 20, 2015 at 3:55:22 PM UTC-5, Madness wrote:
Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?


Mpfffff....

This lamp was used by Zenith and more than a few other manufacturers in the 1950s/1960s as an indicator lamp (on/off) at about the time that radio manufacturers started to become concerned about user-servicing and hot-chassis radios - something that never really bothered them in the past. The worked on the theory that a neon lamp was far less likely to burn out than the old standby #44 or #47, so that loose fingers were less likely to get nipped. ASIDE: Audio devices held on to incandescent lamps (With specific reference to the 47) well into the 80s, before shifting - very slowly - to LEDs or Fluorescent lamps. But, they had transformers on board to isolate the chassis.

It is designed to operate at ~120V AC. It _CAN_ operate at ~120V DC, but only one post will light. It will trip (glow) at about 90V +/-.

Unless there is a voltage dropper in the circuit, it will fail quickly at 220 or 240 V - that is voltages outside of Japan and the Americas. As supplied, it has a 100K resistor in series with the lamp. For conversion to 220V, I have heard values of up to an *additional* 220K in series. Try there and work back if you wish to operate at 220V.


It will fail immediately without a series resistor.
As others have said, there is no resistor built into the lamp.

From a 1965 Allied Radio catalog, Chicago Miniature lamp:
NE-51 is clear glass tubular, single contact bayonet base.
Voltage across the lamp is 65V when operating at the rated 1/25 watt.

A higher voltage is necessary to ionize the neon (which is why a
relaxation oscillator works). The voltage is somewhat constant with
varying current. At 1/25 watt and 65 volts the current would be 0.6 mA
and the series resistor for 120V supply would be 91k (minimum).

There is also a NE-51H that runs at a blinding 1/7 watt (2 mA).


As about 2/3 of my hobby time is dedicated to vintage radios, I am quite familiar with, and keep a bunch of these lamps in my spares-box.

Peter Wieck
Melrose Park, PA


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Old December 3rd 15, 02:27 AM posted to sci.electronics.repair
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Default NE-51 Neon Bulbs



"Fred McKenzie" wrote in message
...
In article ,
Madness wrote:

Just acquired a bunch of these lamps. They're in the same mini-bayonet
style as lamps like the #44/47. But would anyone know if these lamps can
be connected directly to 120 volts? Or do they need a resistor, @ if so,
what value?


Madness-

NE-51 does NOT have a resistor inside!

One thing you can do with them, is build a relaxation oscillator. From
a 90 to 100 volt DC source, connect a series resistor, with a capacitor
across the bulb. Perhaps 470K Ohms and 1 uF. Try different values to
change the flashing rate. For smaller values, it can be used as an
audio oscillator.

Another variation is to have several bulbs, each with its series
resistor. But the capacitors are connected from bulb to bulb in a ring.
The result is a somewhat random flashing. I once built one with 5
generic neon lamps using two small 45 Volt batteries in series. Some
people would become engrossed, trying to figure out the flashing
sequence!

Fred


Ha ! I built one too when I was an apprentice. I seem to think that the
circuit was in Practically Witless magazine. There used to be an aerosol
deodorant at the time which had a blue spherical cap. I had about 12 neons
in my version, and had them poked through holes in one of those caps - a bit
like a WW2 sea mine. Quite by chance, the neon that flashed slowest was the
one that poked vertically out of the top. It was all run from a single 90
volt battery, housed in a box made from modeling plasticard under the
deodorant cap. The one thing that I do recall is that it also had a switch
to alter the way the neons flashed. I seem to remember that one leg of all
the neons were joined together and connected to battery -ve. Likewise, one
leg of all the caps were joined together. When they were left 'floating',
the flash of the individual neons was very 'soft' and hypnotic and random.
The switch took the commoned capacitor legs to battery -ve. With the switch
closed, the flashes were much 'sharper' making the whole display much more
'frenetic' looking. The current drain was so small that a battery lasted a
year or more (which was just as well, as they were expensive. I think I
still have a bunch of neons somewhere. I might try knocking one up again ...
:-)

Arfa



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